1. Field of Invention
This invention relates to vehicle diagnostics, and more particularly to the automated analysis of coil and capacitor conditions in the ignition system of an internal combustion engine.
2. Description of the Prior Art
It has been common for the diagnostic analysis of the electric ignition system of internal combustion engines to be performed primarily in dependence upon an operator's interpretation of a waveform of the low coil voltage, as displayed upon an oscilloscope. This is due in part to the fact that it is relatively costly and time consuming to analyze the condition of the individual components of the ignition system. For instance, although it is easy to determine when the breaker point capacitor is shorted, it has heretofore been difficult to determine the likelihood of the capacitor being open. Similarly, although an open coil is reasonably easy to diagnose, short circuiting of some of the turns of the coil and intermittent arc-overs of the coil have heretofore been difficult to determine. One problem with the graphic analysis of the spark characteristics is that it is highly dependent upon the interpretive skill of the operator. Further, subtle variations from a normal pattern, such as those that result from intermittent arcs or a few shorted turns of the coil, are difficult to observe. In addition, the cathode ray tube circuitry required for a presentation of the spark is rather delicate in contrast with the harsh environment in which vehicle diagnostics are normally performed.